validationinterface: only send zmq notifications for active

doc/zmq.md

@@ -113,11 +113,11 @@ Where the 8-byte uints correspond to the mempool sequence number.
     | hashtx | <32-byte transaction hash in Little Endian> | <uint32 sequence number in Little Endian>
 
 
-`rawblock`: Notifies when the chain tip is updated. Messages are ZMQ multipart messages with three parts. The first part is the topic (`rawblock`), the second part is the serialized block, and the last part is a sequence number (representing the message count to detect lost messages).
+`rawblock`: Notifies when the chain tip is updated. When assumeutxo is in use, this notification will not be issued for historical blocks connected to the background validation chainstate. Messages are ZMQ multipart messages with three parts. The first part is the topic (`rawblock`), the second part is the serialized block, and the last part is a sequence number (representing the message count to detect lost messages).
 
     | rawblock | <serialized block> | <uint32 sequence number in Little Endian>
 
-`hashblock`: Notifies when the chain tip is updated. Messages are ZMQ multipart messages with three parts. The first part is the topic (`hashblock`), the second part is the 32-byte block hash, and the last part is a sequence number (representing the message count to detect lost messages).
+`hashblock`: Notifies when the chain tip is updated. When assumeutxo is in use, this notification will not be issued for historical blocks connected to the background validation chainstate. Messages are ZMQ multipart messages with three parts. The first part is the topic (`hashblock`), the second part is the 32-byte block hash, and the last part is a sequence number (representing the message count to detect lost messages).
 
     | hashblock | <32-byte block hash in Little Endian> | <uint32 sequence number in Little Endian>
 

src/zmq/zmqnotificationinterface.cpp

@@ -173,6 +173,9 @@ void CZMQNotificationInterface::TransactionRemovedFromMempool(const CTransaction
 
 void CZMQNotificationInterface::BlockConnected(ChainstateRole role, const std::shared_ptr<const CBlock>& pblock, const CBlockIndex* pindexConnected)
 {
+    if (role == ChainstateRole::BACKGROUND) {
+        return;
+    }
     for (const CTransactionRef& ptx : pblock->vtx) {
         const CTransaction& tx = *ptx;
         TryForEachAndRemoveFailed(notifiers, [&tx](CZMQAbstractNotifier* notifier) {